How it works
Put the number in for the letter, then work it out in order.
2n + 9 when n = 1 is 2 × 1 + 9 = 11.
Formulas work the same way: put the numbers in for the letters.
Worked examples
An expression
- When n = 1, 2n + 9 = ?
- Replace n with 1: 2 × 1 + 9.
- Multiply first, then add.
- So the answer is 11.
The perimeter of a square
- When s = 0.5, P = 4s = ?
- P = 4s, and s = 0.5.
- 4 × 0.5 = 2.
- So the answer is 2.
The area of a triangle
- When b = 4 and h = 12, A = 1/2bh = ?
- A = 1/2 b h, with b = 4 and h = 12.
- 1/2 × 4 × 12 = 24.
- So the answer is 24.
A taste of the worksheet
These are the first problems of set A. The printable sheet has many more, with an answer key.
- When p = 3, 2 + 3p = __
- When n = 5, n − 4 = __
- When t = 15, t ÷ 5 + 6 = __
- When y = 7, 20 − 2y = __
- When a = 10, 12 − a = __
Words to know
- substitute
- To put a number in for a letter.